The present invention relates to data storage. In particular, the present invention is a data storage cartridge used to house a data storage disk having a shutter assembly with a stress relief mechanism.
Optical storage devices are an alternative technology to conventional magnetic technology because of their high density data storage. In optical recording, data is represented as an optically readable domain on a recording medium such as an optical disk. Optically readable data can be recorded on a disk using a variety of mechanical or optical techniques.
Debris is a significant concern in data recording systems. Debris degrades the optical and/or mechanical performance of an optical disk and optical disk drive. For example, debris can undesirably attenuate the beams used for read or write operations, cause loss of tracking, disk tilt, loss of data and in some cases, drive head crashes (i.e., physical contact of the head with the disk surface). Data storage problems attributable to debris become more pronounced as media aerial density increases and disk tracking tolerances are reduced.
To alleviate the problems introduced by debris, many types of cartridges have been developed for housing data storage disks. Disk storage cartridges include a housing assembly that provides a system of partially redundant barriers that significantly reduce the possibility of debris accumulation on a disk surface.
One known disk cartridge includes a housing having an opening to access a disk contained therein. A shutter assembly is operably coupled to the housing. During operation of the drive the shutter assembly is in an open position, allowing the drive to access the disk surface. When not in operation the shutter assembly is in a closed position over the opening in the housing to protect the disk surface and reduce the accumulation of debris on the disk surface.
The data cartridge components are preferably manufactured in high volume via an injection molding process using a thermal plastic, such a polycarbonate, as the molding material. Generally, for molding plastic by an injection molding machine, the process from closing the die to opening the die to take out the moldings is usually repeated as one production cycle. The time required for the one production cycle depends principally on injection time and cooling time. For achieving an improved productivity, acceleration of the production cycle by shortening the cooling time is utilized.
However, shortening the cooling time within the die can result in moldings which deform or warp after being taken out of the die. In FIG. 1, a prior art shutter assembly used with a disk cartridge is illustrated. The shutter assembly 20 includes a first sidewall 22, a second sidewall 24, an endwall 26, a first interior comer 28 and a second interior comer 30. In reference also to FIG. 2, after injection molding of the thermal plastic, the die is cooled. During cooling of the die, the outside surface 32 of shutter assembly 20 tends to cool at a different rate than the interior surface 34. When the shutter assembly 20 is removed from the die, the internal stresses present at first interior corner 28 and second interior corner 30 (e.g., due to uneven cooling temperatures and sharp corner mold flow directions) tend to undesirably pull first sidewall 22 and second sidewall 24 together (as indicated by arrows 36A, 36B and 36C). As such, it is desirable to provide a shutter assembly design such that after the shutter assembly is removed from the die in the mold process, the first sidewall remains substantially parallel to the second sidewall.
The present invention provides a disk cartridge for use with a disk drive. This disk cartridge includes a housing assembly having an opening for accessing a disk and a molded shutter assembly operably connected to the housing assembly. The molded shutter assembly is moveable between a closed position across the opening, and an open position allowing access to the disk by a disk drive. The molded shutter assembly includes a first sidewall, a second sidewall, and an endwall extending between the first sidewall and the second sidewall. A first joint is defined by the junction of the first sidewall and the endwall. A stress relief mechanism is positioned at the first joint such that the first sidewall is controllably maintained in a desired position relative to the second sidewall after removal from a mold assembly. In one aspect, the first sidewall is maintained substantially parallel to the second sidewall after removal of the molded shutter assembly from a mold assembly.
In one embodiment of the present invention, a disk is operably positioned within the housing assembly. In one aspect, the stress relief mechanism is molded integral to the molded shutter assembly and is geometrically shaped. In one aspect, the stress relief mechanism is a depression. At least a portion of the stress relief mechanism is formed in the endwall. Alternatively, at least a portion of the stress relief mechanism is formed in the first sidewall, or at least a portion of the stress relief mechanism may be formed in the first sidewall and the endwall.
The shutter assembly is made of a polymeric material, such as acetyl, and formed by injection molding. A second joint is defined by the junction of the second sidewall and the endwall. A second stress relief mechanism is positioned at the second joint. The second stress relief mechanism extends along the length of the second joint. Either of the first or second joints may be rounded. The disk cartridge may further include an outer housing operably positioned about the housing assembly.
In another embodiment, the present invention provides a disk cartridge. The disk cartridge includes a housing assembly having an opening for accessing a disk. A molded shutter assembly is operably connected to the housing assembly. The molded shutter assembly is moveable between a closed position across the opening and an open position allowing access to the disk by a disk drive. The molded shutter assembly includes a first sidewall, a second sidewall, and an endwall extending between the first sidewall and the second sidewall. A first joint is defined by the junction of the first sidewall and the endwall. Means are provided for relieving stress between the first sidewall and the endwall, positioned at the first joint, whereby the first sidewall is maintained substantially parallel to the second sidewall after removal from a mold assembly.
In one aspect, the means for relieving stress is molded integral the molded shutter assembly. The disk cartridge includes a disk operably positioned within the housing assembly.
In another embodiment, the present invention provides a disk cartridge including a housing assembly having an opening for accessing a disk, and a molded shutter assembly operably connected to the housing assembly. The molded shutter assembly is moveable between a closed position across the opening and an open position allowing access to the disk by a disk drive. The molded shutter assembly includes a first sidewall having a first major surface, a second sidewall having a second major surface, and an endwall extending between the first sidewall and second sidewall. The endwall has a third major surface. A first interior joint is defined by the junction of the first major surface and the third major surface. A surface depression is positioned at the first interior joint maintaining the first sidewall substantially parallel to the second sidewall after removal from a mold assembly.
In one aspect, the surface depression is geometrically shaped, and molded integral to the molded shutter assembly. The surface depression may be substantially round. At least a portion of the surface depression may be formed in the first major surface, the third major surface, or the first and third major surfaces.
A second interior joint is defined by the junction of the second major surface and the third major surface. The second surface depression is positioned at the second interior joint. In one embodiment the first surface depression extends along the length of the first interior joint. In another embodiment, the endwall is generally arc shaped.